Angular acceleration sensor

ABSTRACT

An angular acceleration sensor comprising two inertia bodies located at opposed positions with respect to the axis of rotation of an angular acceleration to be sensed and movable in a direction tangent to the circumference of such rotation; valve mechanisms operated in response to movement of said inertia bodies for deriving fluid pressure signals in accordance with the direction of motion of said inertia bodies, fluid elements for cancelling acceleration components other than the angular acceleration of rotation about said axis of rotation, gate valve means for deriving a signal corresponding to the average of fluid pressure signals input thereto, and an additional fluid element for operating an actuator proportionally with applied fluid pressure signals representative of the angular acceleration of rotation to be sensed.

United States Patent [191 Ito et al.

[ 1 Oct. 30, 1973 Filed:

ANGULAR ACCELERATION SENSOR Inventors: Shin Ito; Fmihiro Ushijima, bothof Toyota-shi, Japan Assignee: Toyota Jidosha Kogyo Kahushiki Kaisha,Toyota-shi, Aichi-Ken,

Jan. 28, 1972 Appl. No.: 221,518

Foreign Application Priority Data Mar. 2, l97l .Japan 46/10393 Int. Cl.G05d 13/34 Field of Search 91/419; 137/38, 39, 137/40, 45, 46; 180/104;244/78, 80; 303/24 R, 24 A, 24 B, 24 BB, 24 C, 24 F; 73/505, 510, 515

References Cited UNITED STATES PATENTS Borcher et al. 7 3/15 X 3,513,7105/1970 Bates et al. 73/515 X Primary ExaminerRobert G. NilsonAttorney-T0ren & McGeady 57 ABSTRACT An angular acceleration sensorcomprising two inertia bodies located at opposed positions with respectto the axis of rotation of an angular acceleration to be sensed andmovable in a direction tangent to the circumference of such rotation;valve mechanisms operated in response to movement of said inertia bodiesfor deriving fluid pressure signals in accordance with the direction ofmotion of said inertia bodies, fluid elements for cancellingacceleration components other than the angular acceleration of rotationabout said axis of rotation, gate valve means for deriving a signalcorresponding to the average of fluid pressure signals input thereto,and an additional fluid element for operating an actuator proportionallywith applied fluid pressure signals representative of the angularacceleration of rotation to be sensed.

6 Claims, 4 Drawing Figures PATENTEUUCI 30 ms SHEET 1 OF 3 g (90) as '826 IIIAWIIIIIIIII' ANGULAR ACCELERATION SENSOR BACKGROUND OF THEINVENTION This invention relates to an angular acceleration sensor, andmore particularly to a sensor of rotational acceleration for controllingthe posture of automobiles, airplanes or the like in cases whererotational displacement such as yawing or the like occurs.

In order to cope with situations where the braking forces to left andright vehicular wheels become uneven, due to disturbances'such as, forexample, a wind gust, and controllability is lost by oscillatingphenomenon due to yawing, a so-called adapting steering method has beenproposed in which the rate of rotation of yawing is sensed and changesin the posture of wheels is corrected in conjunction .with the powersteering system regardless of the driving operation.

Hitherto, gyro or vortex type fluid elements have been utilizedinangular acceleration sensors for controlling steering when yawing isencountered. The gyro type fluid element, however, is too high in costand its durability leaves much to be desired, because the life ofbearings used therein is short. The vortex type fluid element has manydisadvantages such as low sensitivity, low output level and highconsumption of operating fluid. I

In view of the foregoing, an object of this invention is to provide asensor for angular acceleration of rotation which is simple inconstruction and can be manufactured at low costs but ensures accuratesensing with high output and decreased consumption of operating fluid. II

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated and described preferredembodiments of the invention.

I DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a view in perspective of an automobile used to describe thedirections of force acting thereupon;

FIG. 2 is a schematic circuit diagram of a sensor according to thepresent invention;

FIG. 3 is a schematic diagram of a modified embodiment of the sensor ofFIG. 2; and u I FIG. 4 is a sectional view of a gate valve mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, thelongitudinal direction is represented by the X axis, the lateraldirection by the Y axis, and the vertical direction by the Z axis withthe center of gravity of a vehicle body shown at O. The axes intersectperpendicularly to each other and it will be apparent that there willusually'occur six basic types of motions; that is, motion parallel tothe three axes, rolling motion rotating about the X axis, pitchingmotion rotating about the Y axis and yawing motion rotatin g about the Zaxis. The embodiments of this invention provide sensors which areresponsive only to the angular acceleration of yawing about the Z axisand are not affected by the acceleration components developed by othermotions.

Referring now to FIG. 2, a first valve mechanism 10 and a second valvemechanism 30 of the same construction are arranged at positions oppositeto each other, for example, at symmetrical positions with respect to anaxis of rotation 1 which represents the Z axis, and spaced therefromequivalentdistances in the direction of the X axis intersecting at rightangles said axis of rotation 1. The valves 10 and 30 are provided withfour pressure dischar'ge'ports 12 through 15 and 32 th'roug'h'35,respectively, in their respective chambers ll and 31, said four pressuredischarge ports being arranged at symmetrical positions. Moreover, saidvalves 10 and 30 are provided with inertia bodies 16 and 36,respectively, which are movable in the direction of the Y axisintersecting at right angles the X axis and prependicular to the axis ofrotation 1. Furthermore, the valves 10 and 30 are respectively providedwith passages 17, 18 and 37, 38 at. both lateral sides of the chambers11 and 31, and fluid pressures are supplied into said passages throughorifices 19, 29 and 39, 40. The passages also include output ports 21,22 and 41, 42, respectively.

In the valve 10, the same fluid pressure is supplied into the passages17 and 18. In a case when no inertia force developed by acceleration dueto motion is applied to the inertia body 16, or in a case when acceleration components exist but they are not applied in the direction of the Yaxis, the inertia body 16 remains at a central position within thechamber 11. At this time, the fluid pressure admitted from the passage17 or 18 is discharged from the pressure discharge ports 12 through 15,thus developing no fluid pressure atthe output ports 21 and 22. When theinertia force due to acceleration is applied in the direction of the Yaxis, the inertia body 16 is moved to the left or right in accordancewith the direction of application of said inertia force, thus closingthe passage 17 or 18 on the side to which the inertia body 16 has beenmoved. Consequently, a fluid pressure is developed at the output port 21or 22 on the closed side. The valve 30 is operated in the ssme manner.As a result, referring to the motions shown in FIG. 1, the motions dueto accelerations in the directions of the X and Z axes, and the motiondue to rotation about the Y axis, do not operate to move the inertiabody -16 in the direction of the Y axis,

thus excluding the sensing of such motions. However,

fluid pressure is developed by rotation about the X and Z axes and dueto acceleration components in the direction of the Y axis, thus makingthe device sensitive to these types of motion.

Thus, half of the six motions of a vehicle body can be excluded fromsensing by means of the configurations of the valves 10 and 30 and theirlocation with respect to the axis of rotation 1. However, two moreacceleration components must be eliminated in order that the device willonly sense the angular acceleration of rotation about the Z axis. Forthis purpose, a fluid pressure calculating circuit 50 is provided.

The fluid pressure calculating circuit 50 comprises two fluid elements60 and having the characteristics of proportional type elements, andbeing of the same construction. Fluid elements 60. and 70 comprise inputports 61 and 71, control ports 62, 63 and 72, 73, output ports 64, 65and 74, and pressure discharge ports 66, 67, 68 and 76 77, 78,respectively. In the first fluid element 60, the output port 21 of thefirst valve 10 is connected to the control port 62 through a passage 23,

and the output port 41 of the seco'nd'valve 30 is connected to anothercontrol port 63 through a passage 43. In the second fluid element 70,another output port 42 of the second valve is connected to anothercontrol port 73 through a passage 24. Thus, both fluid elements 60 and70 are operated in the same manner. Therefore, the operation of saidfluid elements will be described with reference to the fluid element 60.When a signal exists at the control port 62 and 63, an outputcorresponding to said signal is developed at the output port 65 or 64.If there is no difference between the signals at the control ports 62and 63, there will be no difference between the outputs at the outputports 64 and 65. Conversely, if there is a difference between thesignalsat the control ports 62 and 63, an output corresponding to saiddifference will be developed at the output ports 64 and 65.Consequently, in view of the above-described relationship between thevalves 10 and both inertia bodies 16 and 36 are moved to one side in thecase of motion in the direction of the Y axis, or rotation about the Xaxis, thus developing signals representing fluid pressure at the outputports 21, 41 or 22, 42. These signals are cancelled by each other at thefluid element 60 or 70. In the case of the motion due to rotation aboutthe Z axis, the inertia bodies 16 and 36 are moved in oppositedirections, thus developing fluid pressure signals at the output port 21of the first valve 10 and the output port 42 of the second valve 30, orat the output port 22 of the first valve 10 and the output port 41 ofthe second valve 30. Thus, outputs are derived. at the output ports 65,75 or 64, 74 by means of the fluid elements 60 and 60.

The fluid pressure calculating circuit further comprises two gate valves80 and 90. The output port 64 of the first fluid element is connected toone of the input sides of the first gate valve 80 through a passage 51having a throttle 100. The output port 74 of the second fluid element isconnected to another input side of the gate valve' 80 through a passage52 having a throttle 101. The output port 65 of the first fluid element60 is connected to one of input sides of the second gate valve 90through a passage 53 having a throttle 102. The output port of thesecond fluid element 70 is connected to another input side of the gatevalve 90 through a passage 54 having a throttle 103. Thus, both gatevalves and are operated in conjunction with the throttles and 103 todevelop a signal corresponding to the mean value of both inputs. In thecase of clockwise rotation about the Z axis, the output ports 64 and 74of the fluid elements 60 and 70 derive outputs, thus actuating the firstgate valve 80. In the case of counterclockwise rotation, the outputports 65 and 75 of the fluid elements 60 and 70 derive the outputs, thusactuating the second gate valve 90.

The fluid pressure caclulating circuit 50 further comprises a thirdfluid element having the same proportional characteristics as said fluidelements 60 and 70. The fluid element 1 10 comprises an input port 111,control ports 112, 113, output ports 114, 115, pressure discharge ports116, 117 and adjusting ports 118, 119. The output side of the first gatevalve 80 is connected to the control port 112 through a passage 55. Theoutput side of the second gate valve 90 is connected to the control port113 through passage 56. Passages 57 and 58 having orifices 104 and 105,respectively, are connected to the adjusting ports 118 and 119. Thethird fluid element 110 is provided with an actuator 120 which isoperated in response to the sensed angular acceleration of rotation.Said actuator 120 is provided with a piston 121. A chamber 122 of saidactuator 120 is connected to the output port 114 of the third fluidelement 110 through a passage 123, and another chamber 124 is connectedto the output port 115 through a passage 125. Thus, in the third fluidelement 110, the output at the output port 114 becomes equal to theoutput at the output port 115 in the case where the fluid pressure isapplied to both adjusting ports 118 and 119 and the angular accelerationof rotation about the Z axis is eliminated by adjusting theorifices 104and 105,

thus preventing erroneous operation due to the variations in themanufacture of the fluid elements 60, 70 and other components. When asignal is passed to the control port 1 12 by the action of the firstgate valve 80, an output is derived at the output port 115, thus movingthe piston 121 of the actuator 120 to the left. When a signalis passadto the other control port 113 by action of the second gate valve 90, thepiston 121 is moved to the right by the output derived at the outputport 114. The angular acceleration of rotation about the Z axis issensed by means of the fluid pressure calculating circuit 50 of theabove-described construction. The overall operation will be describedhereinbelow.

When an angular acceleration of rotation of a t9/dt is developed in adirection of clockwise rotation about the axis of rotation l at thezaxis, an inertia force of m.l. (1 0/d): (in mass of inertia body, l=distance between the axis of rotation at the center of gravity and theinertia body) is applied to the inertia bodies 16 and 36 of both valves10 and 30 in opposite directions. Consequently, a fluid pressure of HA.m.l. LPG/d! (A cross-sectional area of the passage 18 and 37) is derivedat the output ports 22 and 41, respectively. The signal corresponding tosaid fluid pressure is passed to the control ports 63 and 73 of thefirst and second fluid elements 60 and 70, thus deriving an output ofa.1/A. M. (1 0/(1: (a constant or proportionality of the fluid element)at the output ports 64 and 74. These outputs are applied to the firstgate valve 80 and are added to develop an output of QB' 1/A -m'ld t9/dt(B constant determined by the characteristic of the gate valve) at theoutput side. This output is applied to the control port 112 of the thirdfluid element 110.'Finally, an output of 'a'B'y'l/A -m-ld tildt ('yconstant of proportionally of the fluid element) is derived at theoutput port 115 of the third fluid element 110. The piston 121 of theactuator 120 is moved to the left by means of said fluid pressuresignal. Conversely,- if the angular acceleration in the direction ofcounterclockwise rotation about the Z axis is developed, the piston 121of the actuator 120 is moved to the left by means of the fluid pressureproportional to said angular acceleration of rotation.

Not only in .the case where no acceleration component acting in thedirection of the Y axis is applied to the inertia bodies 16 and 36, butalso in the case where acceleration components other than the angularaccel eration of rotation about the axis of rotation 1 are developed,they are cancelled by the fluid elements 60 and 70, and therefore theactuator 120 is not operated. In a case where said accelerationcomponents and the angular acceleration of rotation about the axis ofrotation 1 of dG/dt are simultaneously developed, the actuator 120 isoperated in accordance with the angular acceleration of rotation aboutthe axis of rotation 1 without being affected by other accelerationcomponents.

In addition to the first embodiment as described above, this inventionproposes a second embodiment which is illustrated in FIG. 3. Referringnow to FIG. 3, the axis of rotation land the valves and are constructedin the same manner as the embodiment illustrated in FIG. 2. Two gatevalves 80 and 90 areprovided in the fluid pressure calculating circuit50. The output port 21 of the first valve 10 is connected to the inputside of the first gate valve 80 through a passage 23' having thethrottle 100. The output port 42 of the second valve 80 is alsoconnected to the input side of the first gate 80 through a passage 43having the throttle 101. The output port 41 of the second valve 30 isconnected to the input side of the second gate valve 90 through apassage 44' having the throttle 102. The output port 22 of the firstvalve 10 is also connected to the input side of the second gate valve 90through a passage 24' having a throttle 103. The output sides of theabove-described gate valves 80 and 90 are respectively connected to thecontrol ports 62 and 63 ofthe single fluid element through passages 51'and 52. The output ports 64 and of said fluid element 60 are connectedthrough the passages 55 and 56 to the fluid element 110 of the sameconstruction as the one shown in FIG. 2.

When the angular acceleration of rotation about the axis of rotation 1is developed, this embodiment is operated in a reverse manner astheabove-described first embodiment. First, the fluid pressure signalsproduced in the valves 10 and 30are averaged by means of the gate valvesor 90. Then, this signal is applied through the fluid elements 60 and110 to the actuator 120. At this'time, the gate valves 80 and 90 do notperform averaging of the acceleration components other than the oneabout the axis of rotation. The fluid pressure is applied to the fluidelement 60 and is cancelled by the characteristic of said fluid element60.

Concerning the gate valves 80 and 90, the diaphragm type gate valve asshown in FIG. 4 may be employed in the embodiments in which theabove-described throttles are used in combination. Referring now to FIG.4, the first diaphragm type gate valve 80 will be described. A body 81is divided into four chambers 86 through 89 by means of a nozzle andfirst and second diaphragms 83 and 84 which are integrally connected bymeans of a shaft 82. The first and second chambers serve as the inputside, to which the passages 51 and 52 as shown in the embodiment of FIG.2 are connected. The third chamber 88 serves as the pressure dischargeside. The fourth chamber 89 acts as the output side. The fluid pressureis supplied into the one side of said fourth chamber 89, and thepassage55 is connected to another side thereof. Thus, the input is applied tothe first and second-chambers 86 and 87, and the pressure is dischargedfrom the nozzle 85 by the displacement of the first and seconddiaphragms 8 3 and 84 in accordance with said input. At the same time,the output fluid pressure of the passage 55 is determined. In this case,the output fluid pressure is proportional to A AP P A i wherein P is thefluid pressure in the first chamber 86; P the fluid pressure in thesecond chamber 87; A the area of the first diaphragm 83; and A the areaof the second diaphragm. If there exists the relationship A A betweenthe areas A and A of the first and second diaphragms 83 and 84,

the output fluid pressure will be proportional to P P Thus, a signalcorresponding to the average of the two inputs will be derived in thesame manner as described hereinbefore.

As described above, in the angular acceleration sensor of thisinvention, two inertia bodies 16 and 36 are provided at oppositepositions with respect to the axis of rotation 1 of the angularacceleration to be sensed so that they are movable in directions tangentto the circumference of rotation. The: valves 10 and 30 adapted toderive the fluid pressure signal in accordance with the movement of saidinertia bodies 16 and 36 are all that need be provided. Furthermore, thefluid elements 60, 70, 110, gate valves 30, 90 for calculating fluidpressure signals and other component parts are provided, thus making itpossible to sense the angular acceleration of rotation about the axis ofrotation 1. Oil pressure or pneumatic pressure can be used as the fluidpressure in these embodiments. While the operation of the embodimentshas been describedby taking yawing of an automobile as the angularacceleration of rotation to be sensed, this invention may be applied tosensing rolling and pitching by changing the axis of rotation from the Zaxis to the X or Y axis. Furthermore, this invention may be applied toairplanes. As the embodiment of this invention is simple in constructionand comprises a calculating circuit, its useable life is lengthened andthe manufacturing cost can be reduced as compared with the conventionalgyrotype sensors. Moreover, this invention is more advantageous than thesensors employing eddy-current type elements.

While specific embodiments of the invention have been shown anddescribedin detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. An angular acceleration sensor for sensing move ment of an objectabout a predetermined axis of rotation comprising:

a pair of valves each containing an inertia body positioned on oppositesides of said axis and located on a line extending perpendicularly tosaid axis, each of said inertia bodies being movable upon mo tion ofsaid object to control fluid flow through said valves to derive fluidpressure signals therefrom representative of the motion of said object,said inertia bodies being arranged to effect, upon rotation of saidobject about said predetermined axis, pressure signals which aredifferent from pressure signals occurring as a result of other types ofmotion of said object;

fluid logic means receiving said fluid pressure signals from said valvesand operable to distinguish pressure signals occurring as a result ofrotation of said object about said predetermined axis from otherpressure signals; and

actuator means operated in response to the fluid pressure received fromsaid logic means to effect control functions upon rotation of saidobject about said predetermined axis;

said valves comprising a fluid pressure input source,

a pair of conduit means for each of said valves, with the positions ofsaid inertia bodies being operative I to effect selective application offluid pressure flow to said logic meansthrough either one or the otherof said pair of conduit means, and fluid pressure vent ports for ventingsaid fluid pressure input to divert pressure flow from said conduitmeans, said inertia bodies being movable as a result of movement of saidobject to selectively close and open said vent ports to controlapplication of fluid pressure flow to said fluid logic means.

2. A sensor according to claim 1 wherein said fluid pressure vent portsare located in opposed relationship on either side of said lineextending perpendicularly to said predetermined axis.

3. A sensor according to claim 1 wherein said inertia bodies areoperative to close said vent ports only upon movement of said inertiabodies in a direction tangential to the circumference of rotation ofsaid object about said predetermined axis.

4. A sensor according to claim 1 wherein said inertia bodies are movabletangentially to said circumference of rotation of said body about saidpredetermined axis in two opposed directions, with movement in one ofsaid directions being operative to effect application of fluid pressureflow through one of said pair of conduit means, and with movement in theopposite direction through the other of said pair of conduit means.

5. A sensor according to claim 4 wherein said fluid logic means arearranged to effect application of a pressure signal for operation ofsaid actuator means in response to rotation of said object about saidpredetermined axis when said inertia bodies of each of said valves movein opposed directions tangentially of said circumference of rotation.

6. A sensor according to claim 4 wherein said fluid logic means arearranged to avoid application of a pressure signal to said actuatormeans when said inertia bodies of each of said valves move in the samedirection tangentially of said circumference of rotation of said objectabout said predetermined axis.

1. An angular acceleration sensor for sensing movement of an objectabout a predetermined axis of rotation comprising: a pair of valves eachcontaining an inertia body positioned on opposite sides of said axis andlocated on a line extending perpendicularly to said axis, each of saidinertia bodies being movable upon motion of said object to control fluidflow through said valves to derive fluid pressure signals therefromrepresentative of the motion of said object, said inertia bodies beingarranged to effect, upon rotation of said object about saidpredetermined axis, pressure signals which are different from pressuresignals occurring as a result of other types of motion of said object;fluid logic means receiving said fluid pressure signals from said valvesand operable to distinguish pressure signals occurring as a result ofrotation of said object about said predetermined axis from otherpressure signals; and actuator means operated in response to the fluidpressure received from said logic means to effect control functions uponrotation of said object about said predetermined axis; said valvescomprising a fluid pressure input source, a pair of conduit means foreach of said valves, with the positions of said inertia bodies beingoperative to effect selective application of fluid pressure flow to saidlogic means through either one or the other of said pair of conduitmeans, and fluid pressure vent ports for venting said fluid pressureinput to divert pressure flow from said conduit means, said inertiabodies being movable as a result of movement of said object toselectively close and open said vent ports to control application offluid pressure flow to said fluid logic means.
 2. A sensor according toclaim 1 wherein said fluid pressure vent ports are located in opposedrelationship on either side of said line extending perpendicularly tosaid predetermined axis.
 3. A sensor according to claim 1 wherein saidinertia bodies are operative to close said vent ports only upon movementof said inertia bodies in a direction tangential to the circumference ofrotation of said object about said predetermined axis.
 4. A sensoraccording to claim 1 wherein said inertia bodies are movabletangentially to said circumference of rotation of said body about saidpredetermined axis in two opposed directions, with movement in one ofsaid directions being operative to effect application of fluid pressureflow through one of said pair of conduit means, and with movement in theopposite direction through the other of sAid pair of conduit means.
 5. Asensor according to claim 4 wherein said fluid logic means are arrangedto effect application of a pressure signal for operation of saidactuator means in response to rotation of said object about saidpredetermined axis when said inertia bodies of each of said valves movein opposed directions tangentially of said circumference of rotation. 6.A sensor according to claim 4 wherein said fluid logic means arearranged to avoid application of a pressure signal to said actuatormeans when said inertia bodies of each of said valves move in the samedirection tangentially of said circumference of rotation of said objectabout said predetermined axis.